Funds are requested by a group of eleven investigators from six departments at The University of Chicago to purchase an instrument system for the microsequence determination of peptides and proteins. The system (which includes an Applied Biosystems Protein Sequencer, Perkin-Elmer components for high performance liquid chromatography and a Hewlett-Packard minicomputer data unit) will provide complete and automated analysis of peptide and protein primary structure at the subnanomole level. The gas-phase microsequencer represents an important advance over liquid or solid-phase instrumentation for automated Edman degradation in terms of sensitivity, reliability and repetitive yield; it is flexibly programmed to perform coupling, cleavage and conversion operations, resulting in amino acid phenylthiohydantoin derivatives ready for direct identification and quantitation. The HPLC system provides an accurate solvent delivery and proportioning system as well as a sensitive and stable variable wavelength detector for amino acid phenylthiodantoin separation and detection. Finally, the data unit provides computer-assisted analysis which includes baseline subtraction, enhancement of absorbance reading and peak integration. The requested microsequencing system represents a shared, multiuser instrumentation package which would increase the sensitivity of currently available protein sequence determination more than 100 fold and would complete a protein structural analysis facility already existing in the Department of Biochemistry. Location of the requested instrumentation within this environment would also enhance the sharing of information on analytical and sequence approaches and would foster collaboration among the eleven listed investigators. Use of the system would be overseen by our Advisory Committee (consisting of five users plus an outside member) which would have defined responsibilities with regard to instrument operation and the setting of user priorities. Research applications of the microsequencer system span the areas of prokaryotic and eukaryotic molecular biology, membrane proteins and lipoproteins, peptide hormones and hormone receptors, and a variety of enzymes and structural proteins with important biochemical and physiological function. The requested instrumentation would play a pivotal role in permitting sequence determination in each of these cases at the subnanomole level.